Uprising anniversary

The incident came amid reports of protests across the Tibetan plateau ahead of the 50th anniversary of a failed uprising against Chinese rule that led the Dalai Lama, the Tibetan spiritual leader, to flee to India.

Aba has been a flashpoint since police killed at least seven Tibetans after opening fire on an anti-Chinese protest in March last year, according to activists.

Tensions have been mounting for weeks ahead of the 1959 uprising anniversary and Chinese authorities have reportedly increased security in the areas.

Next month also marks a year since peaceful protests, that began on the 49th anniversary of the uprising, escalated into riots in Tibet's capital, Lhasa, and other areas of the plateau.